Packing structure



June 3, 1941. J. F. -WALLACE:

PACKING STRUCTURE Filed June 16., 1939 INVENTOR JO//V WALLACE ATTORNEY Patented June 3, 1941 l, rAcxmGismUc'rURE John F. Wallace, Shaker Heights, Ohio, assignerl to The Cleveland Pneumatic Tool Company,

Cleveland, Ohio,

a corporation of Ohio ApplicationJune 16, 1939, Serial No. 279,395

l Claim. `(Cl. 288-) This invention relates broadly to packings, but

lmore particularly to sleeve-shaped packings l adapted to expand radially internally and externally for aifording a fluid tight joint between two spaced telescoping elements.

' One object of this invention is to produce a new and improved packing particularly adaptable for use in shock absorbing struts for airplanes for effecting a fluid tight joint between the telescoping cylinders.

Another object of this invention is to provide such a strut with a packing mounted between its telescoping cylinders and engageable by the strutpiston for limiting the extension strokes ofthe strut, the packing being-constructed in a manner preventing its axial compression upon engagement by the strut-piston, thereby preventing excessive radial expansion of the packing and at the other end by a ring or retainerll restingon the bottom of a counterbore I9 forming the inner end of the outer cylinder. The annular chamber I1 is capable of communication with the interior of the inner cylinder through one or more ports extending through the inner cylinder adjacent the piston I4.

Resting on the retainer I8 within the counter- -bore I9, there is a sleeve-like packing 2| and a bushing 22 held against endwise movement by a nut 23 screwed within the upper end of the counterbore. The retainer I8 and. bushing 22 are adequately machined to form sliding bearings for the inner cylinder.

the consequential additional friction between the two telescoping cylinders.

Otherobjects and advantages ancillary to the foregoing reside in the specific construction and aggroupment of the .elements peculiar to this structure, as will become 'apparent from a more complete examination of this specification.

In the drawing: V

Fig. 1 is a side elevational view partly in section of a shock absorbing strut embodying the invention.

Fig. 2 is a cross sectional view taken in a plane indicated by line 2--2 in- Fig. l'.

Fig. 3 is a side elevational view partly in section of the packing shown in Fig. 2.

Fig. 4 is a view similar to Fig. 2, illustrating a modification of the invention.

Fig. 5 is a longitudinal sectional view taken-in a plane indicated by line 5 5 in Fig. 4.

Referring to the drawing, I8 and represent the outer and inner cylinders respectively of a shock absorbing strut, the remote ends of the cylinders being closed, the outer one by a cap I2 and the inner one by a similar cap I3, through which caps the shock absorbing strut may be attached to the parts of an airplane whose relative movements are to be cushioned. On the inner end of the inner cylinder II is mounted a piston I4 slidably engaging the inner wall of the outer cylinder, which piston is formed with a central orice I5 through which is free to slide a metering pin I8 carried by the closed end of the outer cylinder. In practice, the diameter of the inner cylinder is materially smaller than that of the outer cylinder I0, thus normally forming between the'two cylinders an annular chamber Il closed at one end of the pistonV Il and Stored within the cylinder Il), there is liquid introduced therein by removing a filler plug 24 screwed within the upper end of the inner cylinder. Thelevel of the liquid is always in the inner cylinder above the piston Il, while the inner cylinder also contains-compressed air active on the liquid and admitted in the cylinder through an air valve 25.

Referring now more particularly to the'invention, the packing structure 2| is preferably sleeveshaped havinganjinternal wall 26 made of resilient or flexible'material-such as rubber and formed with longitudinally spaced Vring-like lips 21 capable of fluid tight engagement with the inner cylinder II. The external wall 28 of the packing is preferably made of the same material as that of the wall 28, and is formed with lips 29 similar to the lips 21. nally through thepacking or more particularly between the walls 26 and 28, there is a rigid sleeve or core 30 preferably made of rigid material such as steel to the interior and exterior o1' which are permanently attached the walls 26 and 28 respectively, which walls may 'be glued or vulcanized to the sleeve 30 to form therewith a vsingle unit. 'Ihe rigid sleeve 30 is mounted to extend from one to the other end of the packtending longitudinally through the wall of the member 3|, there is a plurality of equally spaced metal pins 34 which may be vulcanized or other- Wise secured in position and made to extend from one to the other end'of the member 3|. l

In operation, relative telescoping movements of the cylinders I0 and Il resulting from the land- Extending longitudi- A ing or taxiing of the craft, are normally checked by the displacement of the liquid through the orifice I5 metered by the tapered pin I6. When the compressing load is removed from the strut. that is, when the craft has left the ground, the weight of the landing Wheel carried by the outer end of the cylinder I 0 together with the action of the compressed air stored within the inner cylinder Il above the liquid, will cause the extension of the strut which is limited by the engagement of the piston Il with the retainer I8. Heretofore, the piston engaging the retainer would cause the load to be transmitted to the packing, resulting in the axial compression of the packing and often subject it to such deformation tending to injure the same. To overcome this disadvantage, it has been the practice to secure the retainer I8 rigidly to the outer cylinder by any suitable means such as a screw connection or the like, thereby preventing the thrust of the piston I4 on the retainer to be transmitted to the packing. In the present construction, the thrust of the piston I 4 transmitted to the retainer I8 is resisted by the core 30 of the packing unit 2l, thereby preventing axial deflection of the packingv walls 26 and 28 while aiordiing By using this novel packing, the retainer IB may simply rest on the bottom of the counterbore I9 without' necessitating a special connection while preventing the packing member from being subjected to axial movement.

In the modification shown in Figs. 4 and 5, the axial thrust of the piston Il is resisted by the pins 34 in the manner above referred to in connection with the core 30.

Although the foregoing description is necessarily of a detailed character, in order to completely set forth the invention, it is to be understood that the specic terminology is not intended to be restrictive or` conning and it is to be further understood that various rearrangements of parts and modifications of structural detail may -be resorted to without departing from the scope or spirit of the invention as herein claimed.

I claim:

A packing structure for operation between two telescoping elements including a sleeve-shaped member made of flexible material, longitudinally spaced lips formed on theinner and outer surfaces of said member, and a rigid sleevefmounted concentrically in the wall of said member and extending from one to the other longitudinal end thereof.

JOHN F. WALLACE. 

